Re: [PATCH v2 0/2] of: phandle_cache, fix refcounts, remove stale entry

From: Michael Ellerman
Date: Tue Dec 18 2018 - 18:46:51 EST

Rob Herring <robh+dt@xxxxxxxxxx> writes:
> On Mon, Dec 17, 2018 at 1:56 AM <frowand.list@xxxxxxxxx> wrote:
>> From: Frank Rowand <frank.rowand@xxxxxxxx>
>> Non-overlay dynamic devicetree node removal may leave the node in
>> the phandle cache. Subsequent calls to of_find_node_by_phandle()
>> will incorrectly find the stale entry. This bug exposed the foloowing
>> phandle cache refcount bug.
>> The refcount of phandle_cache entries is not incremented while in
>> the cache, allowing use after free error after kfree() of the
>> cached entry.
>> Changes since v1:
>> - make __of_free_phandle_cache() static
>> - add WARN_ON(1) for unexpected condition in of_find_node_by_phandle()
>> Frank Rowand (2):
>> of: of_node_get()/of_node_put() nodes held in phandle cache
>> of: __of_detach_node() - remove node from phandle cache
> I'll send this to Linus this week if I get a tested by. Otherwise, it
> will go in for 4.21.

I think it can wait to go into 4.21, it's not super critical and it's
not a regression since 4.19.